﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security.Cryptography;
using System.IO;

namespace CRMSystemV2.Common
{
    public class SecurityHelper
    {
        #region 对称加密
        /// <summary>
        /// 加密
        /// </summary>
        /// <param name="pToEncrypt">待加密的字符串</param>
        /// <param name="sKey">加密密钥</param>
        /// <returns></returns> 
        public static string EncryptDES(string pToEncrypt, string sKey)
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            //把字符串放到byte數組中  
            //原來使用的UTF8編碼，我改成Unicode編碼了，不行  
            byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);
            //byte[]  inputByteArray=Encoding.Unicode.GetBytes(pToEncrypt);  

            //建立加密對象的密鑰和偏移量  
            //原文使用ASCIIEncoding.ASCII方法的GetBytes方法  
            //使得輸入密碼必須輸入英文文本  
            des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
            des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
            MemoryStream ms = new MemoryStream();
            CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
            //Write  the  byte  array  into  the  crypto  stream  
            //(It  will  end  up  in  the  memory  stream)  
            cs.Write(inputByteArray, 0, inputByteArray.Length);
            cs.FlushFinalBlock();
            //Get  the  data  back  from  the  memory  stream,  and  into  a  string  
            StringBuilder ret = new StringBuilder();
            foreach (byte b in ms.ToArray())
            {
                //Format  as  hex  
                ret.AppendFormat("{0:X2}", b);
            }
            ret.ToString();
            return ret.ToString();
        }
        /// <summary>
        /// 解密
        /// </summary>
        /// <param name="pToDecrypt">待解密的字符串</param>
        /// <param name="sKey">解密密匙</param>
        /// <returns></returns>
        public string DecryptDES(string pToDecrypt, string sKey)
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            //Put  the  input  string  into  the  byte  array  
            byte[] inputByteArray = new byte[pToDecrypt.Length / 2];
            for (int x = 0; x < pToDecrypt.Length / 2; x++)
            {
                int i = (Convert.ToInt32(pToDecrypt.Substring(x * 2, 2), 16));
                inputByteArray[x] = (byte)i;
            }
            //建立加密對象的密鑰和偏移量，此值重要，不能修改  
            des.Key = ASCIIEncoding.ASCII.GetBytes(sKey);
            des.IV = ASCIIEncoding.ASCII.GetBytes(sKey);
            MemoryStream ms = new MemoryStream();
            CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
            //Flush  the  data  through  the  crypto  stream  into  the  memory  stream  
            cs.Write(inputByteArray, 0, inputByteArray.Length);
            cs.FlushFinalBlock();
            //Get  the  decrypted  data  back  from  the  memory  stream  
            //建立StringBuild對象，CreateDecrypt使用的是流對象，必須把解密後的文本變成流對像  
            StringBuilder ret = new StringBuilder();
            return System.Text.Encoding.Default.GetString(ms.ToArray());
        }
        #endregion
    }
}
